How To Repair A Motorcycle Showa Invert Fork Seals

Properly maintaining your motorcycle will not but proceed it safe, it'll mean it handles and performs at its very best. While most of us wouldn't hesitate to change the engine oil in our bikes every yr, few of us consider the fact that the front fork legs also have oil in, which is being constantly worked as you lot ride.

The rear shock (or two) on your bicycle too incorporate oil, only these tin't be serviced without specialist tools – you can find out how some can be serviced by Yard-Tech suspension for simply £150 past clicking here .

Besides keeping the oil in your forks fresh, at some betoken the seals volition fail. Here'due south how you tin can fix them for yourself…

The oil in your forks gets worked incredibly difficult, so why wouldn't you regularly replace it with a quality lubricant?

How do I look after my motorcycle forks?

Once of the main reasons fork seals get damaged is through pitting and rust on the fork stanchion (or tube / slider) – equally the tubes move upwards and down in the legs, the seals keep the oil in. But any imperfections to the chrome tin can tear the seal, allowing the oil to leak out. Forks with gilt or blackness nitride coatings, for case, don't suffer the pitting of chrome forks; whatsoever damage needs to be checked by a specialist.

Small imperfections in the chrome can be advisedly removed with very fine emery newspaper and some WD-40, but if the damage is too bad they'll have to be re-chromed or replaced. If re-chroming, it'due south important to use a specialist fork repair company, who'll understand how critical the tolerances are.

Basically, like the rest of your wheel, proceed the forks clean. Don't exist tempted to use seal cleaning tools that slide nether the seal while it'south in place – these tin push button grit into the fork body, which will find its way into the damping shims and valve, and ofttimes cause more harm to the seals. If the dust seal that sits on top of the fork leg is letting dirt become by, it – and the oil seal – need replacing.

Pitting to the forks stanchions will apace tear the seals

How long should my fork oil, the seals and bushes last?

How long your fork seals and bushes last will depend on how and where y'all ride – if you're riding in very dusty areas, over a lot of pot-holes (or landing a lot of ham-fisted wheelies) you might find them failing in a few years. Mine were both leaking, just the bike'south 21 years old; it's only done 18,000 miles simply information technology'southward been sabbatum doing naught for almost a decade – those seals volition starting time to perish over time.

Oh, and information technology used to exist owned by the ex-editor of Fast Bikes magazine, though he promises me he didn't ride this like he did press bikes. It was his mum'due south bike before that – mayhap she was a chip of a hooligan.

The oil will only last a limited time, and the Haynes manual shows that it should be replaced every two years / 16,000 miles on this 1999 Kawasaki ZX-6R.

The very all-time manner to keep your forks at their best is to service them. While every two years would be ideal, assuming they have no issues, every three to four years (unless you're on track or riding an awful lot) should be fine. You can service them yourself, but it'south worth knowing that Chiliad-Tech pause – for instance – will do a full strip and rebuild, with new seals, for around £150. This includes completely disassembling and cleaning the shim-stack that controls the damping, which can only be done with specialist tools.

Oil on the stanchions is a sure sign of a blown fork seal

How do I know when my fork seals and bushes need replacing?

The bushes volition habiliment over time, leaving some minor amount of play between the leg and the stanchion. Realistically though, you lot'll see the fork seals neglect outset, and if you're replacing those, you lot might equally well replace the bushes too, especially every bit they take to come out to get the seal out.

The seals are more obvious when they neglect – you'll encounter traces of oil on the fork stanchions about the dust seal; if in that location is any, wipe it make clean so bounce the forks a few times to check information technology wasn't merely road filth.

What parts do I need?

Always supervene upon your seals and bushes as a pair – if ane leg is showing problems, the other won't be far backside. A pair of fork grit seals (the seals you can see) for this 1999 ZX-6R are £20.62 from Kawasaki, while a pair of the oil seals that sit underneath them are £22.08.  And no, y'all can't just replace the dust seal (which is easy to remove without taking the forks autonomously).

Y'all should also ideally supercede the snap ring on each leg that holds the oil seals in place – two of those cost £v.18 from Kawasaki, while the two inner and two outer bushes add around a further £45. That'southward a total of over £92 for OE.

Fortunately, Wemoto offers complete rebuild kits – for this bike you'd become all the seals, snap rings and bushes for only £41.29.

If a fork stanchion is damaged and you need to supervene upon it a new 1 from Kawasaki will set you lot dorsum £244.51. S bent fork leg can sometimes be straightened, simply if information technology's creased it must be replaced. Wemoto sells Italian-made Paolo Tarozzi fork stanchions for £140.28.

You lot'll also demand oil – bank check your Haynes or owner's manual for the correct weight, but it's typically 10W. Having visited the Motorex factory in Switzerland, I tend to choose their lubricants, so I'k using Motorex 10W Racing Fork Oil. On this wheel, after the forks accept been stripped, it requires upwards to 592cc per leg, so two 1-litre bottles were needed at £14 each.

What tools exercise I demand?

This article isn't intended to be all you demand to change the fork seals on whatsoever motorbike. I'one thousand basing it on my 1999 Kawasaki ZX-6R, only your bicycle will take its own unique needs, and then I thoroughly recommend buying a Haynes workshop manual kickoff. My hope is that this will give you lot the confidence to have on the job for yourself, but only with a workshop guide specific to your auto will you have the correct procedure. Remember that Bennetts customers tin relieve a massive twoscore% on Haynes manuals at Bennetts Rewards . You'll too need the following…

• Allen keys
• Spanners
• Socket prepare
• Flat-bladed screwdriver
• A tool to drive the new oil seals and acme bushes in, or a length of pipe that but fits over the exterior of the fork stanchion
• Fork oil level tool, or a vernier caliper, or a ruler
• Forks seal and bush plumbing fixtures tool, or a length of pipe that will fit over the stanchion.
• An bear upon wrench. You might exist able to manage without one, just you'll need an assistant.
• Brake cleaner

A suitably sized piece of tube tin can be used as an alternative to a seal / bush-league fitting tool

How do I alter the fork seals on my motorbike?

Y'all really practise need a make clean space to piece of work on your forks; whatever dirt that gets into them as they're rebuilt will impair their damping performance. If you're looking to fully service the forks, I would recommend you send them to a company like Thou-Tech , as they'll clinically rebuild them, which includes stripping the shim stacks and cleaning them (you demand a lathe to plow the locking nut off). But £150 for the service includes new seals, though you will have to pay for the bushes if they need replacing (they won't be much extra).

If y'all're just replacing the seals and bushes, you'll exist able to get virtually of the break clean, but don't endeavor to remove the shims.

Only work on ane fork leg at a time, to avert mixing parts betwixt the two, which will have worn slightly differently.

Step 1: Current of air off the bound preload and screw down the rebound adjuster

If y'all want to set the preload back where information technology was, count how many turns you make earlier winding it all the way off. Likewise wind the rebound adjusting screw all the way in – it'll brand setting the height of the top cap easier later on.

Always avert using an adaptable spanner if you tin can - this was all I had to fit the fork caps when I loosened them earlier taking them to Nick'south workshop

Footstep 2: Loosen the summit caps

Earlier removing the forks from the bike, loosen the bolts on the top yoke that hold them in place, and the handlebar prune-ons (if fitted). At this stage, don't loosen the lesser yoke bolts. With the forks held in place only by the bottom yoke, you can loosen the fork top caps – they only demand cracking open, but you must not grip the stanchions in a vice (they could be easily distorted) so now is the concluding chance you'll have to do it.

Step iii: Remove the forks

Before dropping the fork legs out, take annotation of where they sit relative to the tiptop edge of the meridian yoke.

You'll already accept taken the wheel out, but you'll besides need to remove the mudguard, calipers and anything else that's fixed to the forks. Make certain yous hang the calipers somewhere on the bike, so the brake lines aren't put under strain.

Step 4: Remove the bottom bolt

The exact method of dissembling forks is going to vary depending on the age of the bike, and whether they're upside-down or correct-way-up; having a Haynes manual is essential.

Never clench the fork stanchion in the vice, so to hold the fork, protect the jaws of the vice and hold onto both of the caliper hangers and every bit much of the metal that makes them up as possible. Still accept care through.

On this ZX-6R, the left fork leg has the axle nut in – remove this to get at the bolt within the lesser of the fork leg, which holds the damper cartridge in place.

By far the easiest manner to remove this commodities from a correct-way-up fork is using an touch on wrench, which will rattle it out. If you tin can't get agree of one, yous should exist able to undo the bolt by asking an assistant to compress the stanchion into the fork leg as difficult as they can – the pressure level from the spring should stop the cartridge from rotating. Of course, there is a Kawasaki tool available to hold the cartridge.

Sentinel out for the washer that sits on the bottom bolt – this is a sealing washer, and should exist replaced on refitting.

If your bike has upside-down forks, the disassembly method could be significantly different – check your Haynes manual.

Step 5: Drain the old oil

Haynes suggests a unlike order to stripping the forks downward, and if you lot're unsure, information technology'south all-time to follow that. Yet, Nick drains the sometime oil out of the bottom bolt hole, pumping the stanchion in and out. Get out it to sit down for equally long as y'all can to drain every bit much as possible.

Similar any oil, collect it and dispose of information technology properly at your local recycling centre.

Step 6: Remove the grit seal

Using a flat-bladed screwdriver, carefully prize the dust seal off the top of the fork leg.

Step 7: Remove the snap ring

With a smaller screwdriver or a selection, remove the snap ring that sits on elevation of the oil seal.

Step viii: Pull the fork stanchion out

Again, the gild will vary co-ordinate to the bicycle, but at this stage Nick has left the fork summit attached to the stanchion because he's fully-removed the bottom bolt that holds the cartridge in, otherwise, the fork top will need to be removed from the damper rod.

To remove the seal on these forks, hold the fork leg steady and pull the stanchion up and outwards sharply until the bushes inside striking each-other and get-go to drive out. You'll need to do this a few times until the seal and bush pop clear and the stanchion is removed. If you've taken the cartridge out with the stanchion, bank check the bottom of the fork leg, where the seat of the cartridge volition probably notwithstanding be sitting.

Step 9: Remove the bushes and seals

Keeping an eye on how everything fits for later, the lesser bush needs to exist prized open with a flat-bladed screwdriver in order to pop it off the bottom of the stanchion, and so the peak bush, followed by its washer and the oil seal tin be slid off.

Pace 10: Remove the cartridge from the stanchion

A full service from a visitor like K-Tech would come across the cartridge itself disassembled and thoroughly cleaned, only that requires a lathe and some specialist noesis.

Bold you remembered to loosen the top cap while the fork leg was notwithstanding in the cycle, unscrew information technology fully and slide the stanchion down. You can and then concur the preload adjuster while loosening off the lock-nut. And so remove the cap, which will enable you lot to remove the damping adjuster rod and the damping cartridge, complete with the washer, spacer, another washer and the spring (annotation how the smaller, tighter coils are at the lesser on this bicycle). Lookout man out for the seat that goes between the lesser of the cartridge and the base of the fork leg – it'll likely still be in the leg.

Lay all the parts out on a make clean bench, ideally on a newspaper workshop towel.

Step 11: Gear up whatsoever pocket-sized pitting

On chrome fork stanchions, run your fingernail along whatever marks or pits to feel for any pocket-size ridges; using 1200 grit emery newspaper and some WD-40, these can be carefully sanded away. Take it very gently though – terminate regularly to expect for the shiny area that you lot're sanding; you but want to take the small lip off, not abrade the rest of the chrome too much.

Remember, if the forks demand re-chroming, go to a specialist that can keep the thickness exactly within tolerance, or the bore of the stanchion might not friction match the seals. Severely damaged stanchions should be replaced.

If, one time the edges take been taken off, yous're left with a hole in the chrome acquired by corrosion, you really should replace the stanchion or have it properly re-chromed. If you were really skint, you could try filling the damage with chemical metal, then sanding it downward, just information technology's not recommended.

Good tip: Sentinel for pitting on the whole stanchion

"While it'due south pitting on the swept area of the fork stanchions that will cause harm to the seals in employ, y'all demand to remove whatever rust and pitting from the surface area to a higher place it too," says Nick Nomikos, possessor and MoT tester at The Ii Wheel Centre in Harpenden . "Whatever imperfections in that location will tear at the new seals when you slide them on."

Step 12: Clean everything

Using a solvent cleaner like brake cleaner, thoroughly clean all the parts of the suspension, using a paper towel or rag with something to poke it down to clean correct within the leg, making certain you don't leave annihilation in in that location. If you have a compressor, accident the parts dry out.

Clean the seal and clip seats in the acme of the fork leg with an annoying cloth.

With everything clean, check for whatever damage, including where the oil seal sits. If you don't have a run-out gauge, you can check the fork stanchion is direct by rolling it on something flat, like a sheet of glass. Likewise check the bound for any signs of damage, and that it's not sagged – the length it should be is in the Haynes transmission; in this case it shouldn't be shorter than 264mm.

You can inspect the bushes for signs of wear, just equally the forks are autonomously it's worth changing them, especially every bit they're less than £xx from Wemoto, or part of the rebuild kit we're fitting here.

You should also check that the damper rod moves freely up and down inside the cartridge – if it doesn't, it'll demand replacing.

Stride xv: Fit the new bottom bush

The new bottom bush will demand gently opening with a flat-bladed screwdriver before it tin can be popped onto the bottom of the stanchion. Then wipe some of the new fork oil on the bush-league and pour a little into the fork leg to lubricate the sides.

Stride 14: Refit the cartridge

Slide the cartridge all the way into the stanchion, making sure the seat is on the bottom – this has to go on the correct way around so that information technology mates with the lesser of the cartridge. You can now refit the bottom bolt and sealing washer. This should be torqued up using the Kawasaki tool to hold the cartridge, but most people will nip it up with an bear upon wrench on a low setting. You can fully tighten it when the fork is reassembled with the spring back in to apply pressure level and an banana compressing it if you don't accept an impact wrench.

Stride 15: Fit the top bush

Push button the stanchion down into the fork leg as far equally it'll get, then wipe some fork oil on the new top bush-league and slide it down over the stanchion until it sits squarely above the recess in the peak of the fork leg.

You'll need a plumbing equipment tool to tap it fully home, or a suitable slice of pipage that will fit over the stanchion. At a push button, you lot could employ a flat-bladed driver to tap information technology dwelling house, moving around 90° with a gentle tap each time until it'southward fully seated, just make sure you accept the washer sat over the peak of the bush-league earlier doing so.

Expert tip: Bulldoze the bush and seal separately

"Some people drive the peak bush, washer and oil seal all down together," says Nick Nomikos, possessor and MoT tester at The Two Bike Centre in Harpenden . "But the extra force going through the oil seal worries me; doing it properly doesn't take much more fourth dimension."

Step 16: Fit the new oil seal

After double-checking the washer is in place above the bush, wipe some fork oil on the lip of the new oil seal, then check which way up it is; the markings should be on the elevation face. Slide the new seal over the stanchion and downward into the top of the fork leg. Using the section of piping again, or a seal-driving tool, button the seal domicile until it's properly seated and the groove is conspicuously visible for the retaining snap prune to get into.

Step 17: Fit the retaining clip and new dust seal

Popular the snap clip into the groove in a higher place the oil seal (utilize the new one that came with the Wemoto kit if you bought that), and so check it's properly seated by rotating information technology. You tin at present run a footling fork oil around the inside of the new dust seal and slide it into identify. This should push down by hand, only y'all tin carefully push the edges downwardly using the side of a screwdriver's shaft if needs be.

Step 18: Prime the cartridge

In that location is a special tool available to pump the damper rod, but yous should be able to reach the rod to practice it by hand. Fully shrink the stanchion and the damper rod, then slowly cascade in the specified corporeality of oil – information technology'll be at the front of the 'Frame, interruption and concluding drive' affiliate in your Haynes manual; on this bike 500cc will be more than than enough for now.

Accomplish in and accept the damper rod to pump it fully up and down ten times. And then pump the stanchion up and down ten times.

Step 19: Gear up the air gap

The quantity of oil you put in isn't every bit important as the altitude it is from the top of the stanchion. After making certain all of the air is out and that the cartridge is full of oil, push the damper rod and the stanchion right downward, and then mensurate the distance from the elevation of the stanchion to the oil. Yous can do this with a ruler or a vernier caliper, merely the easiest manner is with a fork oil level tool, which is basically a graduated tube with an adaptable plate and a syringe. I made one once with a narrow pipe taped to a ruler and an sometime syringe.

Add or remove oil until the air gap is as specified (in the same place in the Haynes transmission). Hither it'south 103-107mm.

Pace 21: Check the pinnacle cap lock nut

The lock nut on the top of the damper rod sets the height of the cap as it screws down. If you'd wound the rebound adjuster all the way downward before removing the tiptop cap, you'll be able to use that to find the right position, and merely screw the lock nut back up to meet the cap. However, if yous didn't, don't screw it all the way in now, instead, gear up the position of the locknut earlier putting the bound back on – on this model, in that location should be 11mm of thread above the nut.

Footstep 20: Fit the spring

Pull the damper rod up then drop the spring down over the rod with the tighter-wound coils to the bottom (this is on my 1999 bike, on the previous model of ZX-6R, they go to the top, so cheque in your Haynes manual). Next drop the washer, and then the spacer, and then the other washer on. Finally, drib the damping adjuster rod back into the damper rod.

Footstep 21: Spiral on the peak cap

If you lot had wound the rebound adjuster all the way in before removing the cap, now but wind the cap back onto the top of the damper rod until the adjuster screw just touches the adjuster rod. Practice Not tighten it whatsoever further; all yous demand to practice at present is wind the lock nut back up to run into and secure against the bottom of the preload adjuster in the top cap. You lot'll need to counter-concord the top of the preload adjuster, not the top cap itself.

The official style is to set the lock nut 11mm downwards, equally described in step 21, then set the bottom of the rebound damping adjuster to exist 25mm from the bottom edge of the preload adjuster – you volition need a Vernier caliper to measure this. Using this method, screw the pinnacle cap downwards until information technology meets the locknut at 11mm, and so tighten the lock nut against the bottom of the preload adjuster, property the top of the adjuster with a spanner.

Step 22: Spiral the stanchion to the fork cap

Pull the stanchion up and screw it onto the fork cap, making sure it's non cantankerous-threaded. Tighten it equally all-time y'all can by hand.

If y'all hadn't fully tightened the bottom bolt (which holds the damper cartridge), have someone compress the fork while yous nip it up.

Stride 23: Finish tightening the fork caps in the bike

Pass the fork dorsum through the acme and bottom yoke, carefully setting the height of it relative to the top border of the top yoke. Of course, make sure both fork legs sit down at exactly the aforementioned superlative on either side.

Only tighten the bottom yoke bolts (to 20Nm on this bike), and then tighten the fork top caps to the correct setting (23Nm hither). Now you can tighten the elevation yoke bolts and refit the clip-on bars, earlier fixing everything else dorsum on.

If yous tin can't do this job yourself, your dealer volition be happy to accept the piece of work on. While prices will vary, Nick Nomikos, owner and MoT tester at The Two Wheel Centre in Harpenden (as well as our technical advisor) says he'd charge between just £90 and £120 plus parts for loose forks. This is a peachy toll, though it also shows the good value of a full service from G-Tech .

Source: https://www.bennetts.co.uk/bikesocial/news-and-views/advice/bike-maintenance/replace-fork-seals-oil-bushes-diy-motorcycle-maintenance

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